Posted By Andy Petrie
Has anyone come across any research into the effects of high temperature on the human body.

I'm looking for medium term exposure, say up to 2 hours with poor ventilation, no water etc.

Thanks

Posted By John Murgatroyd
The following approach should be taken with regard to the control of exposure to excessive heat:

Identify the activities which might give rise to exposure to excessive heat and identify those who are exposed
Introduce simple measures (such as ventilation and shade) where possible and more stringent measures (air conditioning and frequent rest periods) where the temperature consistently exceeds 32o C, particularly if strenuous work is involved
Ensure cool drinks and salt tablets (or food rich in salt) are regularly taken
Provided tinted protective glasses where radiant heat is present (furnaces, rolling mills, glass manufacture, etc)
Shield heat sources with reflective metalised materials
Ensure clothing is thick enough to protect but porous enough to allow evaporation
Shield both the source and the person to reduce the risk of burns
Allow individuals to develop acclimatisation to heat (usually 3 weeks) when first starting or when returning after a break
Special care required when working inside tanks or pipes as high humidity and low air movement can result in heat hyperpyrexia (hence loss of consciousness due to a rise in body temperature being specified as a specific risk under the Confined Spaces Regulations 1997).
The medical screening out of individuals at greater risk (over 50’s, overweight, chronic skin disease where radiant heat, cardiovascular or renal disease)


Due to the fact that convection and evaporation are interrelated, the temperature and the moisture content of the air are important parameters to measure when assessing the risks created by exposure to heat. Such measurements involve taking the wet and dry bulb temperatures of the air in the workplace. The study of the relationship between air temperature and moisture content being termed psychrometry. As radiant heat also plays a part in the heat exchange between the person and the environment a globe thermometer is used to measure the radiant heat exchange, although this is also affected by air velocity. As rates of heat convection and evaporation are affected by the movement of air around the body, air speed also needs to be measured. Therefore, in order to obtain an indication of the thermal environment it is necessary to measure dry bulb, wet bulb and globe temperatures along with air velocity. The wet and dry bulb thermometers are often contained within a sling psychrometer which can be rotated by hand to induce an air current to flow over the bulbs. Whereas a globe thermometer consists of a mercury in glass thermometer placed with its bulb in the centre of a matt black sphere or globe.

Heat indices attempt to combine the various parameters together with the work rate and the clothing worn into a single index which provides an indication of the degree of discomfort or stress to be expected. More details can be found in the RoSPA publication Monitoring for Health Hazards at Work by Frank S Gill and Indira Ashton.

Posted By Andy Petrie
It's quite an unusual situation in that it's actually members of the public, on the tube.

We're about to undertake some work assessing the risk to passengers on trains stopped in tunnels and as anyone who has used the underground in the summer knows, it can get damn hot down there.

This is essentiallly an emergeny situation and therefore the normal workplace controls can't be applied.

Posted By John Murgatroyd
google:
"There were people lying on the floor, some of them were covered in blankets, and there were people fainting. These were the scenes that greeted 4,000 tube users who were trapped underground for 90 minutes today, during the morning rush hour, and in temperatures that nearly reached 100F - this is ‘real’ tube hell. 10 people were taken to hospital and 627 people were treated at the scene for heat exhaustion, after 4 Victoria line trains broke down at Highbury and Islington station this morning. The incident happened after a train stalled as it was leaving the station, and then the train behind broke down, which trapped 2 more trains behind it. Passengers on each train were eventually led to safety by having to walk through the carriages, before the final train could pull into the station. LUL has defended today’s evacuation procedure, claiming its way was quicker and easier. However, the whole thing would have been less hellish if our tubes had proper ventilation."
As for perspiration and water loss. I've been there...the humidity is 100%, so no water evaporates, you just get very wet...you also get hot very fast and have to move to get some sort of "breeze", which you cannot in the tube. Not only that, but the lights were not on, and only emergency illumination was present. Not to mention the thought that it may only be the train you're in, and the others are due soon !